Never too late to get into a TV show. The things aren't time stamped. Just get your hands on the season one DVDs/Blu-rays and get to watching.
As for the sitcoms you mentioned, I said genuinely good and funny. I like the first few seasons of the office, but it just got old and tired after a while. No real character progression, just more of the same really. Unfortunately, I sat through part of an episode of 30 Rock and I was beyond underwhelmed. Haven't even heard of the other two shows.